Bonnet louvers/vents? Battery cooking.

Hi Dudes, What is the opinion of bonnet vents on the mk4 supras, aesthetically and practically? Post my 2 yr back NAT conversion, which is awsome, i am producing mega heat under the hood, so to stop my battery cooking and reducing it's life expectancy by 60% i think the vents would be a good idea. What do you think, not seen any other club members with these? Never had an answer as to why some members move their batteries to the boot ? Herbie.

My battery is in the boot as I have an aftermarket inlet manifold and FMIC and the pipe goes through where the batter would be.

The battery relocation is either to make the engine bay neater, or as mentioned above certain type of intake manifolds require their boost pipe to pass that direction. Ducting could help but don't be fooled. Yeah cold air might enter but how does it escape? TRD style fenders have cuts in them and would aid in this. Another way is ensuring the under trays are removed as well. You could do a before and after temp test with a thermometre in there taped somewhere, drive it for some time on open high way. Then check the gauge and record the value. Then you could do the upgrades and retest and compare results. Otherwise just hook up a temp sensor and gauge and check that instead of the thermometre.

Do you by chance have a turbo blanket?

The bonnet louvre would only aid in preventing the paint from baking on the top or killing it on the underside. That is if it is the black carpet like material found attached under the bonnet.

You could even use spacers with longer bolts under the bonnet hinges to raise the bonnet a bit. You can check then if it has made any difference in temperatures.

I wouldnt worry about it.

I wouldnt worry about it.

I wouldnt remove the undertrays. Youll soon see the rad support beam and steering rack start to go. Delbody 52 had some nice carbon louvers fitted to his oem hood. Worth a check. But if your producing enough heat to cook a battery you may want to loose the hood all together

Heat wrapping the source of the problem to lower the bay temp would be a good start. I have bonnet vents and they do expel some heat but the chassis of the car heats up so much over about 2 hours of driving I need the fans on or the windows open in +20c outside temps. I plan to get my manifolds wrapped. My twin batteries happen to be in the boot already but not because the original one was getting too hot.

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I wouldnt remove the undertrays. Youll soon see the rad support beam and steering rack start to go. Delbody 52 had some nice carbon louvers fitted to his oem hood. Worth a check. But if your producing enough heat to cook a battery you may want to loose the hood all together

Delbody Call me Mike

Heat wrapping the source of the problem to lower the bay temp would be a good start. I have bonnet vents and they do expel some heat but the chassis of the car heats up so much over about 2 hours of driving I need the fans on or the windows open in +20c outside temps. I plan to get my manifolds wrapped. My twin batteries happen to be in the boot already but not because the original one was getting too hot.

 

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Delbody Call me Mike

Oh god. Typo. Sorry Mike

Thanks for the comments guys i had not thought about the air mass entering the engine bay and how it gets out, but at 50 mph + there must be a mass of air escaping from the back and sides of the bulk head. also i am now on my third Bosch battery in three years, and i found out in my last thread that the battery life reduces by 60 to 70% if it is located in a hot area.

I think two rectangular louvered vents with one located directly above the battery, and the other on the offside symetrically placed would help the temperature problem and look pretty good. Herbie.

I cut speed holes in my bonnet coz it looks cool init

They look cool as you say, my fitment will be very similar. I am not a "Go faster stripes man", but i can accept the practicality and aesthetics of the bonnet vents. Herbie.

Heat wrapping works if you can take the residual heat away, basically all heat wrapping does is slow down the heat transfer from the heat supply, it is a bit like people lagging their pipes in their roof space, ok, it will protect the pipes for a couple of days, but with "cold soak" the pipes freeze up, it is based on "leslies cube" science, all insulation does is increase the "U-Value", this is the heat transferred through a give substance for a given time, so you can put anything around your car battery, but in a short period of time the battery will feel the full ambient temperature under the bonnet of your car. The only solution, is to move the battery or provide cooler air to extract the heat. This cooler air will be supplied whilst driving and allow heat to escape when your car is stationary. Sorry for the high tech info i am a qualified HND Mechanical & Electrical Engineer, but still airs on the side of "Fred Dibanah", who just used basics. lol. Herbie.

Just to close this thread here is a pici to see my diy job i did yesterday, i also made a plastic 8mm thick cover for the battery which is located directly below the nearside louvre, i fitted the offside louvre for aesthetic symitary but it is also directly above the turbos conical air intake filter, it will just add a little cold air.

The louvers are supplied with just open air slots, so to avoid rain water ingress i fitted a fine mesh which breaks the velocity of the water and creates just drips onto the water proofed items below. I think the car now looks cool and my battery should have a longer life. Herbie.

BONNET LOUVERS.jpg (618.3 KB)

I decided to put louvre vents at each side of the front bumper the nerside directly below the battery and the offside directly below the turbo air intake filter, i then fitted a three inch diameter pipe from the void inside the bumper into the engine bay. I think they look good and they will supply cool air where it must reduce the temperatures in the affected areas. I made good templates in thin cardboard to gacheive accurate symmetry and took great care with the cutting of the plastic bumper and the 18 swg metal of the bonnet.

I enjoy the DIY on these cars nearly as much as driving it. Feels good at my local pub when some guys say how good they look. Herbie.

BUMP.&.BON.LOUV.OFFSIDE.jpg (738.4 KB)

BUMPER LOUVER.jpg (611.5 KB)

BONNET LOUVRE.jpg (729.1 KB)